Role of electron–phonon coupling in thermal conductance of metal–nonmetal interfaces

Abstract

We theoretically show that the thermal conductance associated with electron–phonon coupling in a metal near a metal–nonmetal interface can be estimated as $h_{\mathrm{ep}}=\sqrt{{\mathrm{Gk}}_p},$ where G is the volumetric electron–phonon coupling constant and $k_p$ is the phonon or lattice thermal conductivity of the metal. The expression suggests $h_{\mathrm{ep}}\text{≈1/}\sqrt{T}$ at temperatures comparable to the Debye temperature of the metal. The predicted values of $h_{\mathrm{ep}}$ fall within the range of conductance values experimentally observed $\text{(0.3–1\hspace{0.5em}}{\mathrm{GW/m}}^2 \mathrm{K}\mathrm{),}$ suggesting that it cannot be ignored, and could even play a dominant role at high temperatures. Predictions of the total thermal conductance, that include both electron–phonon and phonon–phonon interfacial conductances, show reasonable agreement in its temperature dependence with experimental data for TiN/MgO interfaces.